Pb-acid storage batteries, among others, generate gases (e.g., H.sub.2) within their innards during the normal cycling thereof. These gases are vented to the atmosphere via venting systems designed to permit gas passage while trapping electrolyte which is then drained back into the battery cells from whence it came.
There are two types of battery venting systems commonly in use. These types can be classified as either a vertical type or a horizontal type depending on the orientation of the chamber used to trap the electrolyte. In this regard, both types typically include a chamber intermediate a vent/drainage aperture leading to a cell compartment housing the battery's innards and a gas exhaust port leading to the atmosphere. This chamber traps electrolyte passing through the cell vent/drainage aperture and prevents it from traversing to the exhaust port and escaping the battery. Electrolyte trapped in the trapping chamber drains back into the cell through the same aperture from whence it came.
Discrete vent plugs found on many batteries exemplify vertical type vent systems. The plugs typically include a deep, cylindrical chamber which fits tightly into the filler well of the battery. The floor of the chamber slopes toward a central aperture through which the gases pass upwardly and any electrolyte (e.g., splash) entering the chamber drains back into the cell. The top of the chamber has an exhaust port for discharging the gases to the atmosphere. The chamber may also contain a variety of internal baffles to prevent electrolyte from reaching the exhaust port. Separation of the electrolyte from the gas occurs primarily by gravity as the gases rise through the cylindrical chamber and the heavier electrolyte falls to the chamber floor.
Horizontal type vent systems, on the other hand, are most frequently found molded integrally into the battery cover and include an elongated chamber extending horizontally across the top of the battery. The gases passing through the vent/drainage aperture must traverse the length of the chamber before discharge to the atmosphere via an exhaust port laterally remote from the cell vent/drainage aperture. Frequently such designs employ a single exhaust port and manifold capable of venting several trapping chambers. One such horizontal type system (i.e., the "Freedom Battery" sold by the assignee of the present invention) includes both a shallow vertical cylindrical portion and an elongated horizontal portion in its electrolyte trapping chamber.
Small venting/drainage apertures are usually provided in the floor of the electrolyte trapping chamber to minimize entry of electrolyte splash into the trapping chambers while still permitting the gases to pass. None-the-less, the trapping chambers are commonly invaded by electrolyte passing up through the venting/drainage aperture as a result of excessive overcharging, sloshing, splashing, etc. (i.e., due to mishandling, vibration, tilting, or the like). Entry of excessive amounts of electrolyte into the trapping chambers of horizontal systems is a particularly acute problem as such electrolyte can more readily traverse a horizontal chamber than a vertical chamber.
It is the principal object of the present invention to provide an enclosure beneath the venting/drainage aperture of a battery venting system to shield the aperture against electrolyte invasion from the innards of the battery. It is a further object of the present invention to provide a readily moldable such enclosure including a resilient closure wall with a plastic memory. These and other objects and advantages of the present invention will become more readily apparent from the description thereof which follows.